We revisit the Gaussian broadcast channel (GBC) and explore the rate region achieved by purely discrete inputs with treating interference as noise (TIN) decoding. Specifically, we introduce a simple scheme based on superposition coding with identically and independently distributed (i.i.d.) inputs drawn from discrete constellations, e.g., pulse amplitude modulations (PAM). Most importantly, we prove that the resulting achievable rate region under TIN decoding is within a constant gap to the capacity region of the GBC, where the gap is independent of all channel parameters. In addition, we show via simulation that the weak user can achieve a higher rate with PAM than with Gaussian signaling in some cases.

翻译：我们重新审视高斯广播信道（GBC），并探索在将干扰视作噪声（TIN）解码条件下，由纯离散输入所实现的速率区域。具体而言，我们提出一种基于叠加编码的简单方案，其中输入采用从离散星座（例如脉冲幅度调制，PAM）中独立同分布（i.i.d.）抽取的信号。最重要的是，我们证明，在TIN解码下，所得的可达速率区域与GBC的容量区域之间相差一个常数间隙，且该间隙独立于所有信道参数。此外，通过仿真表明，在某些情况下，弱用户采用PAM信令所能获得的速率高于采用高斯信令时的速率。